Oat bran is a nutrient-dense, resource-rich byproduct that is produced from oat milling. Oxidative deterioration is the main reason that limits the utilisation of oat bran. Thus, improving the storage stability of oat bran has become an urgent requirement. This study aimed to investigate the inhibition of oat bran deterioration via steaming, microwaving, and hot-air drying treatments and the effects of these methods on oat bran physicochemical properties and storage stability. Results indicated that, after the three heating treatments, the solubility of oat bran increased and the powder fluidity showed no significant change ( ). Steam-treated oat bran demonstrated increased initial gelatinisation temperature, peak temperature, and enthalpy, significantly reduced peak viscosity, trough viscosity, breakdown value, final viscosity, and setback value, and significantly improved thermal stability ( ). During accelerated storage, oat bran samples subjected to the three heat treatments showed increased sensory scores and L, a, and b values, whereas due to the decrease of lipase activity in oat bran, their fatty acid values and malondialdehyde content increased slowly and were always lower than those of unprocessed oat bran. All three heat treatments could improve the storage stability and the quality deterioration of oat bran during storage due to oil oxidation. Steaming had the most significant effect.

Umami peptides were derived from enzymatic hydrolysis of sunflower seed protein, followed by isolation and identification. The flavourzyme-enzymatic hydrolysates exhibited the highest umami intensity value of 10.72 ± 0.05 and the lowest bitterness, when pH was adjusted to 7.0, the flavorzyme was added at enzyme-to-substrate (E/S) ratio of 1:25 (w/w), then incubated in a temperature-controlled water bath at 55°C, and the hydrolysis time was 480 min. Ultrafiltration, gel filtration chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC) were used to isolate the umami peptides of sunflower seed. Five fractions were obtained after ultra-filtration, fraction with molecular weight 1-3 kDa showed highest umami intensity value 13.93 ± 0.06. Fraction F1, which was purified via sephadex gel filtration chromatography, exhibited high umami value (12.21 ± 0.06), and low bitterness (4.57 ± 0.06). Seven sub-fractions were purified by RP-HPLC, and the umami taste value of F1-4 was the highest (14.16 ± 0.05), which was 1.32 times stronger than that of sunflower seed protein hydrolysates without any purification. Furthermore, the structure of fraction F1-4 was characterized by mass spectrometry, and three peptide fractions were identified, with amino acid sequences of DVNNPANQLD, NNENQLDEYQR, and EFEGGSIEH, respectively.

In order to isolate antioxidant peptides from oats globulin hydrolyzed alcalase, an antioxidant peptide was isolated and purified using ultra-filtration and ion-exchange chromatography. Hydroxyl and 1,1-diphenyl-2-pycrylhydrazyl (DPPH) radical scavenging capacity was analyzed to evaluate the antioxidant activity of peptide. Five fractions were obtained after ultra-filtration, fraction with molecular weight >10KDa showed the strongest hydroxyl and DPPH radical scavenging ability of 58.38 ± 0.87% and 24.53 ± 0.53% (p < 0.05). Fraction C which was purified via ion-exchange chromatography, exhibited the maximum antioxidant activity (IC₅₀ of hydroxyl and DPPH radical scavenging ability was 1.83 ± 0.03 mg mL⁻¹ and 4.11 ± 0.07 mg mL⁻¹) among other fractions (p < 0.05). Subsequently, five antioxidant peptides were identified by electrospray ionization mass spectrometry (ESI-MS/MS), with the amino acid sequence of IRIPIL, FLKPMT, NSKNFPTL, LIGRPIIY, and FNDILRRGQLL, with a molecular weight of 723.50, 735.40, 919.48, 943.59, and 1343.76 Da, respectively.